package com.wlj.util;

import org.apache.commons.lang3.StringUtils;
import org.springframework.security.authentication.AuthenticationManager;
import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
import org.springframework.security.core.authority.SimpleGrantedAuthority;
import org.springframework.security.core.context.SecurityContextHolder;
import org.springframework.security.web.authentication.www.BasicAuthenticationFilter;

import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collection;


/**
 * 登录成功后 走此类进行鉴权操作
 * <p>
 * 当访问需要权限校验的URL(当然 该URL也是需要经过配置的) 则会来到此拦截器 在该拦截器中对传来的Token进行校验
 * 只需告诉Spring security该用户是否已登录 并且是什么角色 拥有什么权限即可
 */
public class JWTAuthorizationFilter extends BasicAuthenticationFilter {

//    private RedisUtils redisUtils;

    public JWTAuthorizationFilter(AuthenticationManager authenticationManager) {
        super(authenticationManager);
    }

    /**
     * 在过滤之前和之后执行的事件
     */
    @Override
    protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain chain) throws IOException, ServletException {
        String tokenHeader = request.getHeader(JwtTokenUtil.TOKEN_HEADER);
        if (tokenHeader == null || !tokenHeader.startsWith(JwtTokenUtil.TOKEN_PREFIX)) {
            chain.doFilter(request, response);
            return;
        }
        // 如果请求头中有token，则进行解析，并且设置认证信息
        SecurityContextHolder.getContext().setAuthentication(getAuthentication(tokenHeader));
        super.doFilterInternal(request, response, chain);
    }

    /**
     * 从token中获取用户信息并新建一个token
     *
     * @param tokenHeader 字符串形式的Token请求头
     * @return 带用户名和密码以及权限的Authentication
     */
    private UsernamePasswordAuthenticationToken getAuthentication(String tokenHeader) {
        // 去掉前缀 获取Token字符串
        String token = tokenHeader.replace(JwtTokenUtil.TOKEN_PREFIX, "");
        // 从Token中解密获取用户名
        String username = JwtTokenUtil.getUsername(token);
        // 从Token中解密获取用户角色
        String role = JwtTokenUtil.getUserRole(token);
        // 将[ROLE_XXX,ROLE_YYY]格式的角色字符串转换为数组
        String[] roles = StringUtils.strip(role, "[]").split(", ");
        Collection<SimpleGrantedAuthority> authorities = new ArrayList<>();
        for (String s : roles) {
            authorities.add(new SimpleGrantedAuthority(s));
        }
        if (username != null) {
            //这里向SpringSecurity声明用户角色，做相关操作放行
            return new UsernamePasswordAuthenticationToken( username , null, null);
        }
        return null;
    }
}
